U.S. patent number 8,623,272 [Application Number 12/050,006] was granted by the patent office on 2014-01-07 for non-magnetic cobalt-palladium dental alloy.
This patent grant is currently assigned to The Argen Corporation. The grantee listed for this patent is Paul J. Cascone, Arun Prasad. Invention is credited to Paul J. Cascone, Arun Prasad.
United States Patent |
8,623,272 |
Prasad , et al. |
January 7, 2014 |
**Please see images for:
( Certificate of Correction ) ** |
Non-magnetic cobalt-palladium dental alloy
Abstract
A non-magnetic cobalt based "noble" metal dental alloy is
provided. The alloy generally contains at least 25 wt. % palladium,
from 15 to 30 wt. % chromium and a balance of cobalt, where to
ensure the alloy is non-magnetic the concentration of chromium in
the alloy is at least 20 wt. %, or if the concentration of chromium
is less than 20 wt. % the combined concentration of chromium,
molybdenum, tungsten, niobium, tantalum vanadium and rhenium is
greater than 20 wt. %.
Inventors: |
Prasad; Arun (Cheshire, CT),
Cascone; Paul J. (Del Mar, CA) |
Applicant: |
Name |
City |
State |
Country |
Type |
Prasad; Arun
Cascone; Paul J. |
Cheshire
Del Mar |
CT
CA |
US
US |
|
|
Assignee: |
The Argen Corporation (San
Diego, CA)
|
Family
ID: |
39766385 |
Appl.
No.: |
12/050,006 |
Filed: |
March 17, 2008 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20080232998 A1 |
Sep 25, 2008 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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60896182 |
Mar 21, 2007 |
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60941908 |
Jun 4, 2007 |
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60978828 |
Oct 10, 2007 |
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Current U.S.
Class: |
420/436;
420/588 |
Current CPC
Class: |
A61C
13/0003 (20130101); C22C 19/07 (20130101); C22C
30/00 (20130101); C22C 1/06 (20130101); A61K
6/844 (20200101); B33Y 70/00 (20141201) |
Current International
Class: |
C22C
19/07 (20060101); C22C 30/00 (20060101) |
Field of
Search: |
;420/436,588
;148/425 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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10136997.2 |
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Jul 2001 |
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DE |
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1595523 |
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Nov 2005 |
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EP |
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1900836 |
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Mar 2008 |
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EP |
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2 421 513 |
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Jun 2006 |
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GB |
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56-189769 |
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Jul 1983 |
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JP |
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WO 2007/042841 |
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Apr 2007 |
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WO |
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Other References
Kinouchi et al., "Pd-Co Dental Casting Ferromagnetic Alloys", J
Dent Res, Jan. 1981, vol. 60, No. 1, pp. 50-58. cited by applicant
.
International Search Report for International Application
PCT/US2008/057253, filed Mar. 17, 2008, Report completed May 30,
2008, mailed Jul. 31, 2008, 2 pgs. cited by applicant.
|
Primary Examiner: Roe; Jessee
Attorney, Agent or Firm: Knobbe Martens Olson & Bear
LLP
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
The current application claims priority to U.S. Provisional
Application No. 60/896,182, filed Mar. 21, 2007, U.S. Provisional
Application No. 60/941,908, filed Jun. 4, 2007, and U.S.
Provisional Application No. 60/978,828, filed Oct. 10, 2007, the
disclosures of which are incorporated herein by reference.
Claims
What is claimed is:
1. A non-magnetic cobalt based dental alloy comprising: at least 30
wt. % Co; at least 25 wt. % Pd; at least 15 wt. % to 30 wt. % Cr;
and at least one alloying material selected from the group
consisting of molybdenum, tungsten, niobium, tantalum, vanadium and
rhenium; wherein the concentration of the at least one alloying
material is dependent on the concentration of Cr in accordance with
the following: where Cr is at least 20 wt. % then the at least one
alloying material is from 0 to 20 wt. %, and where Cr is less than
20 wt. % then the sum of Cr and the at least one alloying material
is greater than 20 wt. %; and wherein the alloy is
non-magnetic.
2. The non-magnetic cobalt based dental alloy of claim 1, wherein
the alloy further comprises up to about 5 wt. % of at least one
additive material selected from the group consisting of aluminum,
boron, cerium, gallium, germanium and silicon.
3. The non-magnetic cobalt based dental alloy of claim 2, wherein
the at least one additive material is selected from the group
consisting of up to 2 wt. % gallium, up to 3 wt. % silicon, up to 1
wt. % boron, up to 3 wt. % aluminum, up to 3 wt. % germanium, and
up to 1 wt. % cerium.
4. The non-magnetic cobalt based dental alloy of claim 1, wherein
the alloy further comprises less than 5 wt. % of at least one trace
additive selected from the group consisting of copper, nickel and
iron.
5. The non-magnetic cobalt based dental alloy of claim 1, wherein
the sum of Cr, Pd and the alloying material ranges from 45 wt. % to
70 wt. %.
6. The non-magnetic cobalt based dental alloy of claim 1, wherein
the alloy composition comprises 44.75 wt. % cobalt, 20 wt. %
chromium, 25 wt. % palladium, 10% molybdenum and 0.25 wt. %
boron.
7. The non-magnetic cobalt based dental alloy of claim 1, wherein
the alloy has a thermal expansion coefficient within the range of
from about 13 to about 18.times.10.sup.-6.
8. The non-magnetic cobalt based dental alloy of claim 1, wherein
the alloy has a liquidus temperature of below about 1350.degree.
C.
9. A dental product comprising: a body for dental application, said
body being formed of a non-magnetic cobalt based dental alloy
comprising: at least 30 wt. % Co; at least 25 wt. % Pd; at least 15
wt. % to 30 wt. % Cr: and at least one alloying material selected
from the group consisting of molybdenum. tungsten, niobium,
tantalum, vanadium and rhenium; wherein the concentration of the at
least one alloying material is dependent on the concentration of Cr
in accordance with the following: where Cr is at least 20 wt. %
then the at least one alloying material is from 0 to 20 wt. %, and
where Cr is less than 20 wt. % then the sum of Cr and the at least
one alloying material is greater than 20 wt. %; and wherein the
alloy is non-magnetic.
10. The dental product of claim 9, wherein the alloy further
comprises up to about 5 wt. % of at least one additive material
selected from the group consisting of aluminum, boron, cerium,
gallium, germanium and silicon.
11. The dental product of claim 10, wherein the at least one
additive material is selected from the group consisting of up to 2
wt. % gallium, up to 3 wt. % silicon, up to 1 wt. % boron, up to 3
wt. % aluminum, up to 3 wt. % germanium, and up to 1 wt. %
cerium.
12. The dental product of claim 9, wherein the alloy further
comprises less than 5 wt. % of at least one trace additive selected
from the group consisting of copper, nickel and iron.
13. The dental product of claim 9, where the sum of Pd. Cr and the
alloying material ranges from 45 wt. % to 70 wt. %.
14. The dental product of claim 9, wherein the alloy comprises
44.75 wt. % cobalt, 20 wt. % chromium, 25 wt. % palladium, 10%
molybdenum and 0.25 wt. % boron.
15. The dental product of claim 9, wherein the alloy has a thermal
expansion coefficient of from about 13 to about
18.times.10.sup.-6.
16. The dental product of claim 9, wherein the alloy has a liquidus
temperature of below about 1350.degree. C.
Description
FIELD OF THE INVENTION
The current invention is directed to an improved dental alloy, and
more specifically to a non-magnetic cobalt based dental alloy
containing at least 25% palladium, and where the combined
concentration of chromium, molybdenum, tungsten, niobium, tantalum
and rhenium is sufficient to ensure a non-magnetic material.
The current invention is also directed to an improved dental alloy,
and more specifically to a non-magnetic cobalt based dental alloy
containing at least 25% gold plus platinum group elements with the
majority of the 25% addition consisting of palladium.
BACKGROUND OF THE INVENTION
Dental alloys employed in the porcelain-fused-to-metal processing
technique may be classified into several groups, including gold
based, palladium based, cobalt based, and titanium based. One of
the most important criteria in deciding which alloy to use is the
cost of the alloy. The cost of the alloy is dependent upon the
commodity prices of the alloy components. For example, in March
2007, the cost of the major components of each the above alloys
was:
Gold $730 per Troy ounce,
Palladium $350 per Troy ounce, and
Cobalt $2.23 per Troy ounce.
The economic advantage of the base metal cobalt is obvious, but the
functional characteristics of base metal alloys do not compare with
those of gold based or palladium based alloys, and for this reason
they are not generally used in dental products. For example, in
general cobalt base metal alloys are more difficult to cast, grind
and bond to porcelain.
There have been numerous attempts to improve the functional
characteristics of cobalt based alloys through the addition of gold
and the platinum group metals (the platinum group metals consist of
platinum, palladium, rhodium, iridium, osmium and ruthenium).
Examples from the prior art are listed in Table 1, below.
TABLE-US-00001 TABLE 1 SUMMARY OF PRIOR ART Author US Pat. #
Comments Prosen 4,253,869 Describes a cobalt chromium alloy with 7
to 15 wt. % ruthenium. Prosen 4,255,190 Describes a cobalt chromium
alloy with 7 to 15 wt. % ruthenium with gallium. Zwingmann
4,382,909 Describes a cobalt chromium alloy that with 1 to 70 wt. %
palladium. Prasad 4,459,263 Describes a cobalt chromium alloy with
5 to 15 wt. % ruthenium. Vuilleme 6,613,275 Describes a cobalt
chromium alloy with 0.5 to 4 wt. % gold. Prasad 6,656,420 Describes
an alloy with 25 to 60 wt. % gold and up to 2 wt. % ruthenium
balance cobalt. Prasad 6,756,012 Describes a cobalt chromium alloy
with up to 20 wt. % platinum or palladium, up to 10 wt. % gold and
up to 6 wt. % ruthenium.
In each case, some improvement in the functional characteristics of
the base metal alloy has been achieved through the addition of gold
and/or the platinum group metals. However, to date no successful
commercial formulation of a cobalt based high palladium content
alloy has been obtained that is consistent with the American Dental
Association (ADA) guidelines for "noble" alloys required for use in
dental products (i.e. alloys having at least 25% gold or
palladium).
For example, although the Zwingmann patent discloses a wide range
of possible cobalt based palladium alloys, most of these have
strong magnetic properties. Likewise, Ivoclar Vivadent, Inc.
manufactures a cobalt based high palladium content alloy sold under
the tradename Calisto CP, which has a composition of 56 wt. %
cobalt, 10 wt. % chromium, 26.2 wt. % palladium, 3 wt. % tungsten
and 2 wt. % gallium. However, this alloy is also strongly magnetic
and therefore poses potential problems for use in dental
applications. Specifically, magnetic dental inserts and appliances
can make it difficult if not impossible to use advanced imaging
techniques such as Magnetic Resonance Imaging (MRI) on patients. In
addition, such magnetic materials can cause false positives when
individuals are scanned during security check-ins (for example, at
airports). Accordingly, a need exists for improved cobalt based
"noble" dental alloys that possess non-magnetic properties.
SUMMARY OF THE INVENTION
The invention is directed to improved cobalt based palladium
containing alloys that are rendered non-magnetic through the
additions of higher concentrations of other alloying elements.
In one embodiment, an exemplary cobalt based alloy in accordance
with the current invention has the following composition: at least
25 wt. % palladium and 15 to 30 wt. % chromium, where either at
least 20 wt. % of the alloy must be formed of chromium, or if the
concentration of chromium in the alloy is less than 20 wt. % then
the total combination of additive materials selected from the group
consisting of chromium, molybdenum, tungsten, niobium, tantalum,
vanadium and rhenium must be greater than 20 wt. %. An alternative
statement of this composition can take the form of the following
equation: Co.sub.100-y(Pd.sub.aCr.sub.bX.sub.c).sub.y
where X is a material selected from the group consisting of
chromium, molybdenum, tungsten, niobium, tantalum, vanadium and
rhenium; where y is at least 45 wt. %; and where a is at least 25
wt. %, b is from at least 15 wt. % to 30 wt. %, and c is dependent
on the concentration of b in accordance with the following: where b
is at least 20 wt. % then c is from 0 to 20 wt. %, and where b is
less than 20 wt. % then the sum of b and c is greater than 20 wt.
%. In an alternative of such an embodiment, y may range from at
least 45 wt. % to 70 wt. %.
In another embodiment, an exemplary alloy in accordance with the
current invention is formed having the following composition:
cobalt 44.75 wt. %, chromium 20 wt. %, palladium 25 wt. %,
molybdenum 10 wt. % and boron 0.25 wt. %.
In still another embodiment, the alloys in accordance with the
current invention may be modified with gallium up to 2 wt. %,
and/or silicon up to 3 wt. %, and/or boron up to 1 wt. %, and/or
aluminum up to 3 wt. %, and/or germanium up to 3 wt. %, and/or rare
earth elements such as cerium up to 1 wt. %.
In yet another embodiment, the alloys in accordance with the
current invention may include traces amounts of other compatible
materials, such as, for example, nickel, iron and copper.
In still yet another embodiment, indium and tin may be used to
substitute for other deoxidizing elements such as, for example,
gallium and aluminum.
The alloys in accordance with the current invention may be cast and
processed using standard dental laboratory equipment and materials.
Furthermore, they are also suitable for use with newer CAD/CAM and
powder metallurgical applications where no casting is required.
In one embodiment, an exemplary cobalt-chromium in accordance with
the current invention has the following composition: 20 to 30 wt %
chromium, at least 25 wt % from the group consisting of palladium,
iridium, osmium, ruthenium, platinum, rhodium, and gold, where the
majority of the 25% addition consists of palladium, and from 0 to
10% molybdenum. In a preferred embodiment, at least 24 wt % of the
additive is palladium, the remaining materials making up no more
than 1 wt % of the addition.
In another embodiment, an exemplary alloy in accordance with the
current invention is formed having the following composition:
cobalt 45 wt %, chromium 25 wt %, palladium 25 wt %, and gallium 5
wt %.
In still yet another embodiment, the alloy in accordance with the
current invention is able to be cast and processed using standard
dental laboratory equipment and materials.
In still yet another embodiment, the alloy in accordance with the
current invention may be modified with gallium up to 5.0 wt %
and/or silicon up to 3 wt % and/or boron up to 1 wt %.
In still yet another embodiment, the alloy in accordance with the
current invention may be modified with additions of niobium or
rhenium up to 5 wt %.
BRIEF DESCRIPTION OF THE FIGURES
The above-mentioned and other features of this invention and the
manner of obtaining and using them will become more apparent, and
will be best understood, by reference to the following description,
taken in conjunction with the accompanying figures. The figures
depict only typical embodiments of the invention and do not
therefore limit its scope, wherein:
FIG. 1 provides a table (referenced hereinafter as Table 3)
containing a listing of exemplary alloy compositions in accordance
with the current invention and their properties, as well as alloy
compositions outside of the compositional ranges of the current
invention for comparison purposes.
DETAILED DESCRIPTION OF THE INVENTION
This invention provides a non-magnetic cobalt based dental alloy
capable of meeting the ADA requirements for a "noble" alloy that
comprises at least 25 wt. % palladium and an additive of at least
15 to 30 wt. % chromium, where either at least 20 wt. % of the
alloy is chromium, or if the concentration of chromium is less than
20 wt. % then the total combination of additive materials selected
from the group consisting of chromium, molybdenum, tungsten,
niobium, tantalum, vanadium and rhenium must be greater than 20 wt.
%.
This invention also describes a non-magnetic cobalt based dental
alloy containing at least 25% gold plus platinum group elements
with the majority of the 25% addition consisting of palladium
capable of meeting the ADA requirements for a "Noble" alloy.
As used herein, the term "non-magnetic" refers to materials that
possess only diamagnetic properties, that is, that demonstrate
neither ferromagnetic nor paramagnetic properties.
The inclusion of at least 25 wt. % palladium in the cobalt based
dental alloy of the current invention has both metallurgical and
economic benefits. Consider the price of gold and the platinum
group metals: Rhodium $6,200 per Troy ounce, Platinum $1,360 per
Troy ounce, Ruthenium $530 per Troy ounce, Gold $730 per Troy
ounce, Iridium $450 per Troy ounce, Osmium $400 per Troy ounce, and
Palladium $350 per Troy ounce.
Based on this pricing, palladium is by far the lowest costing
element of the group so it is an economic advantage to utilize
palladium in place of gold and other platinum group elements in the
fabrication of a "noble" alloy.
From a metallurgical perspective, palladium and cobalt are
completely soluble in each other. Palladium also substitutes for
molybdenum, tungsten and chromium in cobalt based alloys, allowing
for the use of lower chromium concentrations. Palladium is also
very effective in lowering melting temperature, acts as an alloy
strengthener, is a thermal expansion adjuster for the alloys, and
improves the alloys' oxidation and corrosion resistance. However,
thus far a non-magnetic cobalt based alloy containing at least 25
wt. % palladium has not been formulated that meets all of the
requirements for use in dental products. In the current invention,
a non-magnetic low chromium cobalt-palladium alloy has been
formulated that meets the requirements for use in dental alloys.
The alloy has the following general composition 15 to 30 wt. %
chromium; from 0 to 20 wt. % molybdenum and/or tungsten, tantalum,
niobium, vanadium and rhenium; at least 25 wt. % palladium; and the
remainder cobalt; where to obtain the non-magnetic properties
necessary for dental applications either the concentration of
chromium must be at least 20 wt. % or the where the concentration
of chromium is less than 20 wt. % then the combined concentration
of chromium, molybdenum, tungsten, niobium, tantalum, vanadium and
rhenium in the alloy must be greater than 20 wt. %.
Although not specified in the above formulation of the alloy, it
should be understood that in a preferred embodiment the alloy
contains a minimum concentration of cobalt of at least 30 wt.
%.
The alloy may also include other additives to improve specific
properties, such as the casting or grain refinement properties.
These additional materials include gallium, silicon, boron,
germanium, aluminum and cerium in concentrations of up to 5.0 wt.
%. More specifically, the concentration compositional ranges of
these additional materials are: gallium up to 2 wt. %, and/or
silicon up to 3 wt. %, and/or boron up to 1 wt. %, and/or aluminum
up to 3 wt. %, and/or germanium up to 3 wt. %, and/or cerium up to
1 wt. %.
In the current invention, a cobalt-chromium alloy has been
formulated that meets the requirements for use in dental alloys.
The alloy has the following general composition 20 to 30 wt %
chromium; at least 25 wt % from the group consisting of palladium,
iridium, osmium, ruthenium, platinum, rhodium, and gold, where the
majority of the 25% addition consisting of palladium; 0 to 10 wt %
molybdenum; and the remainder cobalt.
The alloy may also include other additives to improve specific
properties, such as the casting or grain refinement properties.
These additional materials include gallium up to 5.0 wt % and/or
silicon up to 3 wt % and/or boron up to 1 wt % and niobium or
rhenium up to 5 wt % and tungsten and up to 10% molybdenum.
In a preferred embodiment, at least 24 wt % of the additive is
palladium.
Exemplary compositional ranges for alloys contain these additional
additives are provided below: Palladium 25%; Cobalt 40 to 55%;
Chromium 20 to 30%; Gallium 0 to 5%; Tungsten 0 to 10%; Molybdenum
0 to 10%; and Silicon 0 to 1%.
The increased palladium content of about 25 wt % can in some
embodiment reduce the need for large additions of molybdenum or
tungsten. The gallium addition lowers the melting range so that the
alloy may be cast with a gas-oxygen torch. The small silicon and
boron additions can also be used to improve the alloy's
castability. If the alloy is to be cast by induction heating then
the melting range can be higher reducing the need for any of these
additives.
One exemplary alloy in accordance with the current invention is
formed having the following composition: cobalt 45 wt %, chromium
25 wt %, palladium 25 wt %, and gallium 5 wt %.
Exemplary compositional ranges for alloys contain these additional
additives are provided in Table 2, below:
TABLE-US-00002 TABLE 2 EXEMPLARY ALLOY COMPOSITIONAL RANGES Element
Min Best Max Co bal bal bal Cr 15 20 30 Pd 25 25 30 Mo and/or W,
Ta, Nb, V, Re 0 10 20 Al 0 0.5 3 B 0 0.25 1 Ce 0 0.25 1 Ga 0 1 5 Ge
0 1 3 Si 0 0.5 3
The palladium content of at least 25 wt. %, and palladium's general
enabling effect, can in some embodiments reduce the need for large
additions of other materials such as chromium, molybdenum,
tungsten, etc. However, key to the current invention is the
requirement that the material as formed be non-magnetic. The
inventors of the current invention have discovered that alloying
cobalt with palladium and chromium within certain weight
percentages, and optionally with the addition of molybdenum,
tungsten, niobium, tantalum, vanadium, rhenium or other suitable
elements in specific amounts, renders these alloys nonmagnetic.
Specifically, it has been discovered that where the alloy has a
content of chromium of at least 20 wt. %, or where the alloy has a
content of chromium of at least 15 wt. % and the combined
concentration of chromium, molybdenum, tungsten, or other suitable
additive materials is greater than 20 wt. %, a non-magnetic
cobalt-palladium alloy may be reliably formed. The properties and
compositions of exemplary alloys formed in accordance with the
current invention, including an example outside the compositional
ranges of the current invention for comparison, are provided in
Table 3 in the attached figure.
As shown in Table 3, alloys formed in accordance with the present
invention exhibit non-magnetic properties as previously discussed;
however, they also exhibit a wide variety of other physical
properties that make them particularly promising for use in dental
applications. For example, the alloys show liquidus temperatures
below 1400.degree. C. (typically below 1350.degree. C.), which
makes them adaptable for use with all standard casting, molding and
shaping processes, as well as with new non-casting procedures. In
addition, the alloy compositions of the current invention can be
ground using traditional dental laboratory grinding media, making
the alloy suitable for use with newer CAD/CAM and powder
metallurgical applications where no casting is required. Substrates
or final restorations can be milled from blocks made from these
alloys. As powders, these alloys can be used either to create three
dimensional performs utilizing appropriate binders and then be
sintered or directly be sintered/melted such as for example, with a
laser, to create substrate or final restoratives. Exemplary
disclosures of such processes can be found, for example, in U.S.
Pat. Nos. 7,084,370 and 6,994,549, the disclosures of which are
incorporated herein by reference. It should be understood that
while some prior art laser sintering techniques specify a specific
range of useable alloy particulate sizes, the alloys of the current
invention are contemplated for use in laser sintering techniques
over all possible particulate size ranges.
Also, as shown in Table 3, in addition to the improved castability
of these materials, the alloys show a wide variety of thermal
expansion coefficients, namely from about 13 to about
18.times.10.sup.-6 (as measured from about 25 to 500.degree. C.).
Because of the wide range of thermal expansion coefficients
accessible by these materials, they can be used with all standard
porcelains on the marketplace, such as, for example, high fusing
conventional porcelains that have thermal expansion coefficients
from about 13 to 15.times.10.sup.-6, and low fusing porcelains that
have thermal expansion coefficients from about 15 to
16.times.10.sup.-6.
In addition to the main components, as previously discussed the
alloys of the current invention may also contain concentrations of
other additives to improve specific properties. For example, small
concentrations (up to .about.5 wt. %) of gallium, silicon, boron,
aluminum, germanium and cerium can serve to deoxidize, lower the
melting range, and improve the castability of the alloys.
Specifically, the addition of gallium can lower the melting range
of the alloy so that the material can be cast with a gas-oxygen
torch. Alternatively, small silicon and boron additions can also be
used to improve the alloy's thermal expansion and castability.
However, it should be understood that these additives are not
essential to the practice of the current invention. For example, if
the alloy is to be cast by induction heating, then the melting
range can be higher eliminating the need for any of these
additives. Regardless, based on its castability and non-magnetic
properties, one particularly preferred non-magnetic alloy in
accordance with the current invention is formed having the
following composition: cobalt 44.75 wt. %, chromium 20 wt. %,
molybdenum 10 wt. %, palladium 25 wt. %, and boron 0.25 wt. %.
It is appreciated that the above compositions suitable for use with
dental appliances are not exclusive. Those of skill in the art will
be aware that some of the materials can be substituted or
additional materials may be added without altering the key
properties of the alloys of the current invention. For example, it
is well known that small amounts of cobalt and palladium can be
substituted with copper, nickel and iron. Alternatively, small
concentrations (less than 5 wt. %) of these materials may also be
added or be found in the alloy as impurities without affecting the
properties of the overall composition.
To prove the utility of these alloys for dental products, exemplar
compositions were successfully bonded to several popular dental
porcelains. The inventors have fully tested the utility of the
materials for dental applications by fabricating both single crowns
and bridgework. In addition, they have shown that alloys in
accordance with the invention can be processed using standard
foundry processing techniques for cobalt alloys, indicating that
the alloys of the invention will be useable with typical mass
production casting and/or molding techniques.
Finally, biological testing has been completed on ruthenium
containing alloys in the past and has determined alloys of this
type to be non-cytotoxic. Although similar cytotoxicity tests have
not been completed for the alloys of the current invention, ion
release tests have been conducted for exemplary alloys, as shown in
Table 3. The results show that the alloys of the current invention
have very low ion release when subjected to immersion tests of the
ISO standard. These low ion release rates suggest that not only
will the alloys of the current invention be non-cytotoxic, but that
they also possess very high electrochemical resistance, which is
important in the oral environment.
Although the above description has focused on a range of
compositions for the alloys of the current invention, the invention
is also directed to a method of manufacturing a dental product
generally comprising the steps of providing an alloy having a
composition in accordance with the above description and then
shaping that alloy using any suitable means. As discussed above,
the alloy of the instant invention allows for the use of a number
of conventional shaping techniques, such as, casting and molding.
Moreover, the alloys of the current invention also allow for the
use of more recent advances in shaping technologies, such as, for
example, selective laser sintering. It should be understood that
any of these techniques or a combination thereof may be used with
the alloys of the current invention.
Those skilled in the art will appreciate that the foregoing
examples and descriptions of various preferred embodiments of the
present invention are merely illustrative of the invention as a
whole, and that variations in the relative composition of the
various components of the present invention may be made within the
spirit and scope of the invention. For example, it will be clear to
one skilled in the art that typical impurities and/or additives may
be included in the compositions discussed above that would not
affect the improved properties of the alloys of the current
invention nor render the alloys unsuitable for their intended
purpose. Accordingly, the present invention is not limited to the
specific embodiments described herein but, rather, is defined by
the scope of the appended claims.
* * * * *